Abstract: A mathematical model of the additional effects of the
liquid in the hydrodynamic gap is presented in the paper. An
incompressible viscous fluid is considered. Based on computational
modeling are determined the matrices of mass, stiffness and damping.
The mathematical model is experimentally verified.
Abstract: High density electrical prospecting has been widely
used in groundwater investigation, civil engineering and
environmental survey. For efficient inversion, the forward modeling
routine, sensitivity calculation, and inversion algorithm must be
efficient. This paper attempts to provide a brief summary of the past
and ongoing developments of the method. It includes reviews of the
procedures used for data acquisition, processing and inversion of
electrical resistivity data based on compilation of academic literature.
In recent times there had been a significant evolution in field survey
designs and data inversion techniques for the resistivity method. In
general 2-D inversion for resistivity data is carried out using the
linearized least-square method with the local optimization technique
.Multi-electrode and multi-channel systems have made it possible to
conduct large 2-D, 3-D and even 4-D surveys efficiently to resolve
complex geological structures that were not possible with traditional
1-D surveys. 3-D surveys play an increasingly important role in very
complex areas where 2-D models suffer from artifacts due to off-line
structures. Continued developments in computation technology, as
well as fast data inversion techniques and software, have made it
possible to use optimization techniques to obtain model parameters to
a higher accuracy. A brief discussion on the limitations of the
electrical resistivity method has also been presented.
Abstract: This paper is aimed to the use of different types of
industrial wastes in concrete production. From examined waste
(crushed concrete waste) our tested concrete samples with dimension
150 mm were prepared. In these samples, fractions 4/8 mm and 8/16
mm by recycled concrete aggregate with a range of variation from 0
to 100% were replaced. Experiment samples were tested for
compressive strength after 2, 7, 14 and 28 days of hardening.
From obtained results it is evident that all samples prepared with
washed recycled concrete aggregates met the requirement of standard
for compressive strength of 20 MPa already after 14 days of
hardening. Sample prepared with recycled concrete aggregates (4/8
mm: 100% and 8/16 mm: 60%) reached 101% of compressive
strength value (34.7 MPa) after 28 days of hardening in comparison
with the reference sample (34.4 MPa). The lowest strength after 28
days of hardening (27.42 MPa) was obtained for sample consisting of
recycled concrete in proportion of 40% for 4/8 fraction and 100% for
8/16 fraction of recycled concrete.
Abstract: In this work, two fermentations at different
temperatures (25 and 30ºC), with cell recycling, were accomplished
to produce ethanol, using a mix of commercial substrates, xylose
(70%) and glucose (30%), as organic source for Scheffersomyces
stipitis. Five consecutive fermentations of 80 g L-1 (1º, 2º and 3º
recycles), 96 g L-1 (4º recycle) and 120 g L-1 (5º recycle)reduced
sugars led to a final maximum ethanol concentration of 17.2 and 34.5
g L-1, at 25 and 30ºC, respectively. Glucose was the preferred
substrate; moreover xylose startup degradation was initiated after a
remaining glucose presence in the medium. Results showed that yeast
acid treatment, performed before each cycle, provided improvements
on cell viability, accompanied by ethanol productivity of 2.16 g L-1 h-
1 at 30ºC. A maximum 36% of xylose was retained in the
fermentation medium and after five-cycle fermentation an ethanol
yield of 0.43 g ethanol/g sugars was observed. S. stipitis fermentation
capacity and tolerance showed better results at 30ºC with 83.4% of
theoretical yield referenced on initial biomass.
Abstract: The use of engineered nanomaterials has increased as
a result of their positive impact on many sectors of the economy,
including agriculture. Silver nanoparticles (AgNPs) are now used to
enhance seed germination, plant growth, and photosynthetic quantum
efficiency and as antimicrobial agents to control plant diseases. In
this study, we examined the effect of AgNP dosage on the seed
germination of three plant species: corn (Zea mays L.), watermelon
(Citrullus lanatus [Thunb.] Matsum. & Nakai) and zucchini
(Cucurbita pepo L.). This experiment was designed to study the
effect of AgNPs on germination percentage, germination rate, mean
germination time, root length and fresh and dry weight of seedlings
for the three species. Seven concentrations (0.05, 0.1, 0.5, 1, 1.5, 2
and 2.5 mg/ml) of AgNPs were examined at the seed germination
stage. The three species had different dose responses to AgNPs in
terms of germination parameters and the measured growth
characteristics. The germination rates of the three plants were
enhanced in response to AgNPs. Significant enhancement of the
germination percentage values was observed after treatment of the
watermelon and zucchini plants with AgNPs in comparison with
untreated seeds. AgNPs showed a toxic effect on corn root
elongation, whereas watermelon and zucchini seedling growth were
positively affected by certain concentrations of AgNPs. This study
showed that exposure to AgNPs caused both positive and negative
effects on plant growth and germination.
Abstract: An efficient remanufacturing network lead to an
efficient design of sustainable manufacturing enterprise. In
remanufacturing network, products are collected from the customer
zone, disassembled and remanufactured at a suitable remanufacturing
facility. In this respect, another issue to consider is how the returned
product to be remanufactured, in other words, what is the best layout
for such facility. In order to achieve a sustainable manufacturing
system, Cellular Manufacturing System (CMS) designs are highly
recommended, CMSs combine high throughput rates of line layouts
with the flexibility offered by functional layouts (job shop).
Introducing the CMS while designing a remanufacturing network will
benefit the utilization of such a network. This paper presents and
analyzes a comprehensive mathematical model for the design of
Dynamic Cellular Remanufacturing Systems (DCRSs). In this paper,
the proposed model is the first one to date that considers CMS and
remanufacturing system simultaneously. The proposed DCRS model
considers several manufacturing attributes such as multi period
production planning, dynamic system reconfiguration, duplicate
machines, machine capacity, available time for workers, worker
assignments, and machine procurement, where the demand is totally
satisfied from a returned product. A numerical example is presented
to illustrate the proposed model.
Abstract: We investigated the structure and electronic properties
of the compound Mg1-xBixO with varying concentrations of 0, ¼, ½,
and ¾ x bismuth in the the cesium chloride (CsCl), zinc-blende
(ZnS), nickel arsenide (NiAs) NaCl (rock-salt) and WZ (wurtzite)
phases. We calculated. The calculations were performed using the
first-principles pseudo-potential method within the framework of spin
density functional theory (DFT).
Abstract: Structural Equation Modeling (SEM) was used to test
a hypothesized model explaining Malaysian hypermarket customers’
perceptions of brand trust (BT), customer perceived value (CPV) and
perceived service quality (PSQ) on building their brand loyalty
(CBL) and generating positive word-of-mouth communication
(WOM). Self-administered questionnaires were used to collect data
from 374 Malaysian hypermarket customers from Mydin, Tesco,
Aeon Big and Giant in Kuala Lumpur, a metropolitan city of
Malaysia. The data strongly supported the model exhibiting that BT,
CPV and PSQ are prerequisite factors in building customer brand
loyalty, while PSQ has the strongest effect on prediction of customer
brand loyalty compared to other factors. Besides, the present study
suggests the effect of the aforementioned factors via customer brand
loyalty strongly contributes to generate positive word of mouth
communication.
Abstract: This paper presents the development of a robot car
that can track the motion of an object by detecting its color through
an Android device. The employed computer vision algorithm uses the
OpenCV library, which is embedded into an Android application of a
smartphone, for manipulating the captured image of the object. The
captured image of the object is subjected to color conversion and is
transformed to a binary image for further processing after color
filtering. The desired object is clearly determined after removing
pixel noise by applying image morphology operations and contour
definition. Finally, the area and the center of the object are
determined so that object’s motion to be tracked. The smartphone
application has been placed on a robot car and transmits by Bluetooth
to an Arduino assembly the motion directives so that to follow
objects of a specified color. The experimental evaluation of the
proposed algorithm shows reliable color detection and smooth
tracking characteristics.
Abstract: In the present study, the kinetics of thermal
degradation of a phenolic and lignin reinforced phenolic foams, and
the lignin used as reinforcement were studied and the activation
energies of their degradation processes were obtained by a DAEM
model. The average values for five heating rates of the mean
activation energies obtained were: 99.1, 128.2, and 144.0 kJ.mol-1 for
the phenolic foam; 109.5, 113.3, and 153.0 kJ.mol-1 for the lignin
reinforcement; and 82.1, 106.9, and 124.4 kJ.mol-1 for the lignin
reinforced phenolic foam. The standard deviation ranges calculated
for each sample were 1.27-8.85, 2.22-12.82, and 3.17-8.11 kJ.mol-1
for the phenolic foam, lignin and the reinforced foam, respectively.
The DAEM model showed low mean square errors (
Abstract: Micro-electromechanical system (MEMS)
accelerometers and gyroscopes are suitable for the inertial navigation
system (INS) of many applications due to low price, small
dimensions and light weight. The main disadvantage in a comparison
with classic sensors is a worse long term stability. The estimation
accuracy is mostly affected by the time-dependent growth of inertial
sensor errors, especially the stochastic errors. In order to eliminate
negative effects of these random errors, they must be accurately
modeled. In this paper, the Allan variance technique will be used in
modeling the stochastic errors of the inertial sensors. By performing
a simple operation on the entire length of data, a characteristic curve
is obtained whose inspection provides a systematic characterization
of various random errors contained in the inertial-sensor output data.
Abstract: Heat transfer of leaves is a crucial factor in optimal
operation of metabolic functions in plants. In order to quantify this
phenomenon in different leaves and investigate the influence of leaf
shape on heat transfer, natural convection for pine, orange and olive
leaves was simulated as representatives of different groups of leaf
shapes. CFD techniques were used in this simulation with the
purpose to calculate heat transfer of leaves in similar environmental
conditions. The problem was simulated for steady state and threedimensional
conditions. From obtained results, it was concluded that
heat fluxes of all three different leaves are almost identical, however,
total rate of heat transfer have highest and lowest values for orange
leaves, and pine leaves, respectively.
Abstract: Ibeno, Nigeria hosts the operational base of Mobil
Producing Nigeria Unlimited (MPNU), a subsidiary of ExxonMobil
and the current highest oil & condensate producer in Nigeria. Besides
MPNU, other oil companies operate onshore, on the continental shelf
and deep offshore of the Atlantic Ocean in Ibeno, Nigeria. This study
was designed to delineate oil polluted sites in Ibeno, Nigeria using
geophysical methods of electrical resistivity (ER) and ground
penetrating radar (GPR). Results obtained revealed that there have
been hydrocarbon contaminations of this environment by past crude
oil spills as observed from high resistivity values and GPR profiles
which clearly show the distribution, thickness and lateral extent of
hydrocarbon contamination as represented on the radargram reflector
tones. Contaminations were of varying degrees, ranging from slight
to high, indicating levels of substantial attenuation of crude oil
contamination over time. Moreover, the display of relatively lower
resistivities of locations outside the impacted areas compared to
resistivity values within the impacted areas and the 3-D Cartesian
images of oil contaminant plume depicted by red, light brown and
magenta for high, low and very low oil impacted areas, respectively
confirmed significant recent pollution of the study area with crude
oil.
Abstract: Pt/γ-Al2O3 membrane catalysts were prepared via an
evaporative-crystallization deposition method. The obtained Pt/γ-
Al2O3 catalyst activity was tested after characterization (SEM-EDAX
observation, BET measurement, permeability assessment) in the
catalytic oxidation of selected volatile organic compound (VOC) i.e.
propane, fed in mixture of oxygen. The VOC conversion (nearly
90%) obtained by varying the operating temperature showed that
flow-through membrane reactor might do better in the abatement of
VOCs.
Abstract: This paper analyzes the conceptual framework of three
statistical methods, multiple regression, path analysis, and structural
equation models. When establishing research model of the statistical
modeling of complex social phenomenon, it is important to know the
strengths and limitations of three statistical models. This study
explored the character, strength, and limitation of each modeling and
suggested some strategies for accurate explaining or predicting the
causal relationships among variables. Especially, on the studying of
depression or mental health, the common mistakes of research
modeling were discussed.
Abstract: Polymer Electrolyte Membrane Fuel Cell (PEMFC) is
such a time-vary nonlinear dynamic system. The traditional linear
modeling approach is hard to estimate structure correctly of PEMFC
system. From this reason, this paper presents a nonlinear modeling of
the PEMFC using Neural Network Auto-regressive model with
eXogenous inputs (NNARX) approach. The multilayer perception
(MLP) network is applied to evaluate the structure of the NNARX
model of PEMFC. The validity and accuracy of NNARX model are
tested by one step ahead relating output voltage to input current from
measured experimental of PEMFC. The results show that the obtained
nonlinear NNARX model can efficiently approximate the dynamic
mode of the PEMFC and model output and system measured output
consistently.
Abstract: Corrosion of concrete sewer pipes induced by
sulphuric acid attack is a recognised problem worldwide, which is not
only an attribute of countries with hot climate conditions as thought
before. The significance of this problem is by far only realised when
the pipe collapses causing surface flooding and other severe
consequences. To change the existing post-reactive attitude of
managing companies, easy to use and robust models are required to
be developed which currently lack reliable data to be correctly
calibrated. This paper focuses on laboratory experiments of
establishing concrete pipe corrosion rate by submerging samples in to
0.5pH sulphuric acid solution for 56 days under 10ºC, 20ºC and 30ºC
temperature regimes. The result showed that at very early stage of the
corrosion process the samples gained overall mass, at 30ºC the
corrosion progressed quicker than for other temperature regimes,
however with time the corrosion level for 10ºC and 20ºC regimes
tended towards those at 30ºC. Overall, at these conditions the
corrosion rates of 10 mm/year, 13,5 mm/year and 17 mm/year were
observed.
Abstract: The article presents two mathematical models of the
interaction between a rotating shaft and an incompressible fluid. The
mathematical model includes both the journal bearings and the
axially traversed hydrodynamic sealing gaps of hydraulic machines.
A method is shown for the identification of additional effects of the
fluid acting on the rotor of the machine, both for a linear and a nonlinear
model. The interaction is expressed by matrices of mass,
stiffness and damping.
Abstract: The potential neuroprotective effect of Phyllantus
nuriri against Fe2+ and sodium nitroprusside (SNP) induced oxidative
stress in mitochondria of rats brain was evaluated. Cellular viability
was assessed by MTT reduction, reactive oxygen species (ROS)
generation was measured using the probe 2,7-dichlorofluoresce
indiacetate (DCFH-DA). Glutathione content was measured using
dithionitrobenzoic acid (DTNB). Fe2+ (10μM) and SNP (5μM)
significantly decreased mitochondrial activity, assessed by MTT
reduction assay, in a dose-dependent manner, this occurred in parallel
with increased glutathione oxidation, ROS production and lipid
peroxidation end-products (thiobarbituric acid reactive substances,
TBARS). The co-incubation with methanolic extract of Phyllantus
nuriri (10-200 μg/ml) reduced the disruption of mitochondrial
activity, gluthathione oxidation, ROS production as well as the
increase in TBARS levels caused by both Fe2+ and SNP in a dose
dependent manner. HPLC analysis of the extract revealed the
presence of gallic acid (20.540.01), caffeic acid (7.930.02), rutin
(25.310.05), quercetin (31.280.03) and kaemferol (14.360.01).
This result suggests that these phytochemicals account for the
protective actions of P. niruri against Fe2+ and SNP -induced
oxidative stress. Our results show that P. nuriri consist important
bioactive molecules in the search for an improved therapy against the
deleterious effects of Fe2+, an intrinsic producer of reactive oxygen
species (ROS), that leads to neuronal oxidative stress and
neurodegeneration.
Abstract: One of the main challenges in using the Discrete
Element Method (DEM) is to specify the correct input parameter
values. In general, the models are sensitive to the input parameter
values and accurate results can only be achieved if the correct values
are specified. For the linear contact model, micro-parameters such as
the particle density, stiffness, coefficient of friction, as well as the
particle size and shape distributions are required. There is a need for
a procedure to accurately calibrate these parameters before any
attempt can be made to accurately model a complete bulk materials
handling system. Since DEM is often used to model applications in
the mining and quarrying industries, a calibration procedure was
developed for materials that consist of relatively large (up to 40 mm
in size) particles. A coarse crushed aggregate was used as the test
material. Using a specially designed large shear box with a diameter
of 590 mm, the confined Young’s modulus (bulk stiffness) and
internal friction angle of the material were measured by means of the
confined compression test and the direct shear test respectively. DEM
models of the experimental setup were developed and the input
parameter values were varied iteratively until a close correlation
between the experimental and numerical results was achieved. The
calibration process was validated by modelling the pull-out of an
anchor from a bed of material. The model results compared well with
experimental measurement.